<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>box</title>
    <style>
        .box {
            width: 300px;
            height: 300px;
            background-color: lightgray;
            /*padding: 10px;   !*四个方向内边距全为10px*!*/
            /*padding: 10px 20px 30px 40px;  !*方向为上右下左*!*/
            /*padding: 10px 20px;  !*上下为10px，左右为20px*!*/
            padding-top: 10px;  /*上*/
            padding-right: 20px;  /*右*/
            padding-bottom: 30px;  /*下*/
            padding-left: 40px;  /*左*/
            border-left: 2px black dashed;
            border-bottom: 2px green solid;
            border-right: 2px purple dotted;
            margin: 20px;
        }
        span {
            display: block;
            width: 300px;
            height: 100px;
            border: 1px solid black;
        }
        .c2 {
            width: 500px;
            height: 300px;
            background-color: darkcyan;
            float: right;
        }
        .c3 {
            width: 500px;
            height: 300px;
            background-color: darkmagenta;
        }
    </style>
</head>
<body>
<div class="c2">aaa</div>
<div class="c3">bbb</div>

<div class="c1">
    <span>达内云计算 Cloud Computing</span>
    <span>达内云计算 Cloud Computing</span>
</div>
<div class="box">

</div>
</body>
</html>